In a cutting tool for grooving or cutting-off, it is desired that generated chips do not abut and damage a processing surface of a workpiece. Thus, it is desirable that after the generated chips move forward along a longitudinal direction of the cutting insert, while the generated chips do not deviate transversely with respect to the longitudinal direction of a cutting insert, the generated chip be curled in a spring shape and be divided in pieces.
For example, PTL 1 discloses a breaker portion which has a Y shape when viewed from an upper side, and in which a tip end portion branches toward both end portions of a front cutting edge, on a rake face of an insert body in a substantial prism shape. In addition, according to PTL 1, the tip end portion which branches toward both end portions has a shape which becomes lower toward a back side from the front cutting edge side.